FH and cancer: Oncometabolites are a group of metabolites, including succinate, fumarate, and 2-hydroxyglutarate, accumulated in cancer cells generally as a consequence of mutations in genes coding for the related metabolic enzymes, that are succinate dehydrogenase (SDH), fumarate hydratase, or isocitrate dehydrogenase, or of alterations in their enzymatic activity (62).